National Geographic photographer Joel Sartore photographs the last two remaining woolly monkeys in North America in the Louisville Zoo for his project the Photo Ark with the help of, from left, zookeeper Silvia Zirkelbach and zoo staff Joanne Luyster. June 23, 2014. Yi-Ke Peng/The Courier-Journal

National Geographic photographer Joel Sartore photographs the last two remaining woolly monkeys in North America in the Louisville Zoo for his project the Photo Ark. June 23, 2014. Yi-Ke Peng/The Courier-Journal

National Geographic photographer Joel Sartore photographs the last two remaining woolly monkeys in North America in the Louisville Zoo for his project the Photo Ark. June 23, 2014. Yi-Ke Peng/The Courier-Journal

National Geographic photographer Joel Sartore photographs the last two remaining woolly monkeys in North America in the Louisville Zoo for his project the Photo Ark. The monkeys were a challenge to shoot as they often reached out of their cage to grab at Sartore. June 23, 2014. Yi-Ke Peng/The Courier-Journal

National Geographic photographer Joel Sartore photographs the last two remaining woolly monkeys in North America in the Louisville Zoo for his project the Photo Ark. June 23, 2014. Yi-Ke Peng/The Courier-Journal

National Geographic photographer Joel Sartore photographs the last two remaining woolly monkeys in North America in the Louisville Zoo for his project the Photo Ark. June 23, 2014. Yi-Ke Peng/The Courier-Journal

National Geographic photographer Joel Sartore photographs the last two remaining woolly monkeys in North America in the Louisville Zoo for his project the Photo Ark. June 23, 2014. Yi-Ke Peng/The Courier-Journal

National Geographic photographer Joel Sartore photographs the last two remaining woolly monkeys in North America in the Louisville Zoo for his project the Photo Ark. June 23, 2014. Yi-Ke Peng/The Courier-Journal